The present invention is directed to a stage assembly for moving a device. More specifically, the present invention is directed to a stage assembly including a reaction assembly for an exposure apparatus.
Exposure apparatuses are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an illumination source, a reticle stage assembly that retains a reticle, a lens assembly and a wafer stage assembly that retains a semiconductor wafer. The reticle stage assembly and the wafer stage assembly are supported above a mounting base with an apparatus frame.
Typically, the wafer stage assembly includes a wafer stage base, a wafer stage that retains the wafer, and a wafer stage mover assembly that precisely positions the wafer stage and the wafer. Somewhat similarly, the reticle stage assembly includes a reticle stage base, a reticle stage that retains the reticle, and a reticle stage mover assembly that precisely positions the reticle stage and the reticle. The size of the images and the features within the images transferred onto the wafer from the reticle are extremely small. Accordingly, the precise relative positioning of the wafer and the reticle is critical to the manufacturing of high density, semiconductor wafers.
Unfortunately, the wafer stage mover assembly generates reaction forces that can vibrate the wafer stage base and the apparatus frame. The vibration influences the position of the wafer stage base, the wafer stage, and the wafer. Similarly, the reticle stage mover assembly generates reaction forces that can vibrate the reticle stage base and the apparatus frame. The vibration influences the position of the reticle stage base, the reticle stage, and the reticle. As a result thereof, the vibration can cause an alignment error between the reticle and the wafer. This reduces the accuracy of positioning of the wafer relative to the reticle, or some other reference, and degrades the accuracy of the exposure apparatus. In light of the above, one object of the present invention is to provide a stage assembly that precisely positions a device. Another object is to provide a stage assembly that minimizes the influence of the reaction forces of the stage mover assembly upon the position of the stage, the stage base, and the apparatus frame. Still another object is to provide a stage assembly having an improved reaction assembly. Yet another object is to provide an exposure apparatus capable of manufacturing precision devices such as high density, semiconductor wafers.
The present invention is directed to a stage assembly that moves a device relative to a stage base. The stage assembly includes a stage, a stage mover assembly, and a reaction assembly. The stage retains the device. The stage mover assembly moves the stage relative to the stage base with at least one degree of freedom. The reaction assembly includes a reaction base that is coupled to the stage mover assembly.
Uniquely, the reaction assembly counteracts the reaction forces generated by the stage mover assembly in the one degree of freedom that is transferred to the reaction base. As a result thereof, the stage assembly can more accurately position the device. Further, the stage assembly can be used in an exposure apparatus to manufacture high density, high quality semiconductor wafers.
As provided herein, the stage mover assembly can include one or more X stage movers and one or more Y stage movers that are coupled to the reaction assembly. The X stage movers move the stage along an X axis, and about a Z axis, while the Y stage movers move the stage along a Y axis. The stage mover assembly generates X reaction forces, Y reaction forces and theta Z reaction forces during the movement of the stage.
In the embodiments provided herein, the reaction assembly includes an X reaction mass, a Y reaction mass, and a reaction mover assembly. The X reaction mass moves along the reaction base to reduce the X reaction forces generated by the stage mover assembly that are transferred to the reaction base. The reaction mover assembly moves the Y reaction mass along the reaction base to counteract the Y reaction forces generated by the stage mover assembly. Additionally, the reaction mover assembly moves the X reaction mass and/or the Y reaction mass to counteract the theta Z reaction forces.
A number of alternate embodiments of the reaction assembly are provided herein. In one embodiment, the reaction base is fixedly secured to the stage base. In another embodiment, the reaction base is free to move relative to the stage base with at least three degrees of freedom. In yet another embodiment, the reaction base is fixedly secured to a mounting base independently of the stage base.
Preferably, the reaction mover assembly includes one or more trim movers that adjusts and corrects the position of the X reaction mass to inhibit an assembly center of gravity of the stage assembly from shifting.
The present invention is also directed to a method for making a stage assembly, a method for making an exposure apparatus, a method for making a device and a method for manufacturing a wafer.